Radio beam antenna and control means therefor



July 8, 1941. w. s.v BURKHART RADIO BEAM ANTENNA AND CONTROL MEANS THEREFOR Filed Nov. 28, 1939 3 Sheets-Sheet 1 147" THRIVE).

1 w. S. BURKHART- RADIO BEAM ANTENNA AND CONTROL MEANS THEREFOR 3 Sheets-'Sheet 2 Filed Nov. 28, 1939 Mz/A/v 592mm 272mm ATTZZF/VE'Y.

July 8, 1941. 2,248,335

RADIO BEAM ANTENNA AND CONTROL MEANS THEREFOR w.- s. BURKHART Filed Nov. 28, 1939 3 Sheets-Sheet 3 ATTJ/M/EX Patented July 8, 1941 UNITED STATES PATENT OFFICE RADIO BEAM ANTENNA AND CONTROL MEANS THEREFOR William Shearman Burkhart, Cincinnati, Ohio Application November .28, 1939, .Serial No. 306,432'j 7 Claims. (01. 250-41) v rotate and accurately position a beam antenna in its most effective compass course.

Another object is to provide an inexpensively constructed rotary beam antenna system with efficient means to accurately adjust the length of its vertical directors and reflectors, at a distance.

'Another' object is to provide independently operable control means for a rotary boom of an antenna system and for each of its elements, which are entirely outside the electrical field of the antenna.

Another object is to provide a rotary beam antenna system with adjustable vertical directors and reflectors which are simple and inexpensive to construct, positive in operation, and exceedingly efficient.

Another object of the invention is to provide an improved boom for a beam antenna system which embodies structural features intended tominimize wind resistance.

The foregoing and suchother objects of the invention'as will become more readily apparent as the description proceeds, will be more readily understood from a perusal of the following specification; in which reference is had to the accompanying drawings, wherein- Fig. 1 is an elevational view of the beam antenna system, showing portions broken away.

Fig. 2 is a horizontal sectional View taken substantially on line 22 of Fig. 1.

Fig. 3 is a fragmentary vertical sectional view fiedform of the director or reflector, showing portions broken away.

'Fig. '7 is a schematic diagram, illustrating the remote control mechanism.

I Successful and efiicient operation of a rotatable beam antenna system requires quick and accurate pointing of the antenna in the direction of the signal to be received or discharged and extremely accurate adjustment in the lengths of the directors and reflectors. It is also essential that, in systemsincluding a-plurality of reflectors and directors, the adjustment of all reflectors and all directors be uniform. Obviously, because of such required exactness, it is'impractical lac-formulate the exact length of the reflectors and directors prior to installation. This'results primarily from variations in reception and broadcasting conditions locally, which are efiected by objects, such as trees, etc., in the" immediate vicinity of the antenna. Because beam antennas are mounted at a considerable elevation'above the ground, it is extremely desirable that the means provided' for accurately varying the lengths of the. reflectors and directors and for pointing the antenna system be controllable at or about ground level.

Referring particularly to the embodiment of the invention illustrated in Fig. l, a horizontal boom I l is rotatable about a fixed vertical radiator l2 which extends above the top of a wooden super-structure l3. 'The radiatorll2 also extends below the top of the super-structure l3 and has its lower end terminate within a housing M vwhich contains suitable connections for electrically joining the radiator, through leads IE, to' the usual broadcasting or receiving equipment, not' 1 shown.

Theboom Ilpreferably consists of a skeleton assembly of wooden joists. l6 and spaced cross pieces I'I wherebya minimum amount of resist ance is offered to wind pressure. As best shown in Fig. 3 a sleeve l8 surrounds the'radiator 2 and has its lower end portion rigidly anchored at l9 to the super-structure. This sleeve l8 provides a vertical axis for the boom H whereby it is free to rotate through a complete circle in a horizontal plane. I

Also mounted for free rotation on the sleeve, below the boom, is a drive assembly (Fig.3) including a bearing plate 2| and a pair of pulleys 22. As shown, the plate 2| andpulleys' 22 are integral or suitably joined rigidly, and the plate is bolted or otherwisesecured to the bottom face of the boom. v

Two V-belts 23 operatively connect the pulleys 22 with another set of pulleys 24 carried on the upper end of an idler shaft 25. The shaft25 extends downwardly from the pulleys 24 and has its lower end journaled in'an indicator housing 26, the purpose of which will be more fully explained hereinafter.

operatively connecting said shaft with a stud shaft 29. A bevel gear M, on the extended endof said stud shaft meshes with a companion bevel gear 32 on the upper end of a vertical drive" shaft 3 3. The lower end of the shaft 33 termi- The shaft 25 also carriesa gear 27 (Fig. 7) mounted within a housing 28 nates in a gear reduction housing 34, preferably formed integral with the housing of an electric motor 35. Both the shafts 25 and 33 preferably are made of hard wood to avoid costly insulation therefor. Operation of the motor 35 rotates the boom ll about the stationary radiator l2.

The extended or opposed arms of the boom carry adjustable directors and reflectors, 36 and 31 respectively. Although two directors and tworeflectors are illustrated it is to be understood that the antenna system will operate efliciently with only one director and one reflector. In other words, the number of reflectors and directors provided is optional, it being well under' stood that an increase in the number of directors and reflectors proportionally increases the strength of the signal forward in the elected direction. When properly adjusted there is little or no signal off the sides or from the back or reflector side of the antenna system.

The directors 36' and refiectors3-l are identical inrconstru-ction and; therefore, only one of these elements: has been illustrated in detail in Figs. 4 and 5: As shown each director or reflector is made-intwovertically aligned identical sections, one of which extends upwardly and the other downwardly of the boom ll. As" bestillustrated in'Figs. 4 and 5, the upper portion of the reflector or director there shown, preferably includes a length of tubing 38' having its lower end firmlyysecured Within the annular flanged plate 39' bolted or otherwise secured tov a" block of: insulation or hard WOOd 4|: secured to the A tubular extension;

each time contact is made.

be: accomplished from the ground or a similar level. Consequently, the lower end of extensi0n'42 is internally threaded, asbest illustrated in Eig..5-at 43, to receive a threaded shaft 44. The: shaft 44 extends axially beyond the lower endiofi thetubing' 38, across the boom and into the tubing 38: of the companion lower section. The portion of 'said'shaft extending'into said companion section also is threaded to engage the internal threads of the lower telescoping extension'. Accordingly, rotation of the shaft 44 in either direction moves the opposed extension members 42 inwardly or outwardly of their respective tubing to decrease or increase the overall. length of the-element.

Rotation of said shaft preferably is effected by providing a worm gear 45' on the shaft 44 between the ends of the two opposed tubes 38 which meshes continuously with a worm 46 car'- ried on a horizontal manually driven shaft 4?. In the event tworeflectors and two directors are provided, as shown in Fig. 1, the shaft 41 will be commonto both reflectors and an identical shaft will be common to both directors whereby upon rotation of either of said shafts both reflectors or'both directors are adjusted in unison to insure identical adjustment of their extension 42. Rotation of' the shaft 41 preferably is effected through a pulley 48- mounted on the shaft and endless belt 49 which depends to within reach fromthe ground. Accordingly, manipulation of the belt 49 to rotate the shaft in one direction or the other positively increases or decreases the length of the element.

Quick and eificient rotation to accurately position the boom H in any selected compass course is best efiected through operation of the selective control mechanism diagrammatically shown in Fig. '7. This control is initiated through operation of a selector, indicated generally at 5!, which aotuates-suitabie mechanism to control starting and stopping of the boom rotating motor 35. As illustrated, the selector preferably includes a dial 52 having finger engaging openings 53, or the like, adapted to be selectively engaged for manually rotating said dial a predetermined distance. Rotation of the selection dial 52 rotates its shaft 54 and also a ratchet disk 55 carried thereon. In the disclosure there are ten openings 53, numbered one to ten consecutively. Clockwise rotation of the selection dial and ratchet disk places a spring 56 on the shaft 54 under tension so that when the dial is released the parts return to their normal or rest position. The disk 55 has the same number of teeth as there are openings 53 in theselection dial;

An insulated control arm 51 is mounted for intermittent engagement by the teeth on the ratchet disk 55. As shown, the arm 51 carries a contact 58- electrically connected through lead" just described to the terminal 66, leads 61', 68'

and 69 to the other'terminal l l' of the step-down transformer 55; thereby energizing the solenoid coil 6| and pulling its armature 12 downwardly The armature T2: is connected by a link T3'to a pawl 14' which is always in engagement with the teeth on acontrol disk 15.

The control disk 75 preferably has thirty-six teeth fora purpose to be described hereinafter; Obviously, each time the circuit is closed at contact 58 and terminal 66; the pawl 141s actuated to rotate the control disk 75' step by step a distance equal to one tooth. Accordingly, should the selection dial be completely or partially rotated, the control disk 15 will rotate a corresponding distance. Thus, to rotate the disk 15 a distance equal to sixteen teeth, the finger opening number 10 is-engag'ed and the dial rotated until the finger engages a stop '16. The dial then is released and it returns to its position of rest. The number 6 opening then is engaged and the dial again rotated until the stop 76 is engaged, whereupon the dial is again released. This operation has caused sixteen impulses to'be transmitted to actuate the pawl 14 sixteen times.

The shaft 1'? upon which'the control disk 75 is mounted also carries a contact arm 18" which is insulated therefrom but electrically connected through leads 19I, to thelead 69'connecting with the step-down transformer terminal H. The contact arm 18 co-operates with a plurality of annularlyarranged terminals 82 which, in this instance number thirty-six. Accordingly, each movement of the control disk F5, through a distance of one tooth, moves the contact arm 18 from one terminal 82 'to the next adjacent ter- Initial. In this manner the contact arm 18 is automatically positioned to make an electrical contact with any one of the terminals 82. A corresponding number of terminals 83 are arranged annularly within the control housing 26 pre-- relay coil 86 leads 8'! and 62, with the stepdown transformer terminal II.

The control mechanism also includes a manually actuated switch 88 which, when closed, completes a circuit from the step-clown transformer terminal II through leads 69, 68, 89, switch 83, lead 9!, hold-down coil 92 and leads 93 and 63 to the transformer terminal 64. While this circuit is closed, the coil 92 is energized thus actuating its armature to close two switches 94 and 95. The closing of switch 95 completes the main line circuit 96 of the motor 35, whereupon the motor operates to rotate the boom II. The other closed switch 94 completes a circuit, flowing through lead 63 from the step-down transformer 65, lead 93, hold-down coil 92, switch 94, lead 9?, switch contact arm 98, terminal 99, lead IIII and then back to the transformer through leads 8| and 69. This circuit energizes the hold-down coil 92 to maintain the two switches 94-95 closed. Thus, the main line circuit 96 remains closed and the motor continues to operate after the key 88 is released.

As the contact finger 84 moves across its associated terminals 83, contact is eventually made with the one terminal 83 electrically connected through its respective lead I02 to the corresponding terminal 82 with which the selectively positioned contact arm I8 is in electrical engagement. A secondary circuit is thus completed which flows from the step-down transformer terminal H through leads 69, 8|, 79 to contact arm 18, associated terminal 82, respective lead I02 to the corresponding terminal 83 and its contactin arm '84, lead 85, holding coil 85, lead 81 and back to the transformer terminal 6 1 through leads 62-63. This circuit energizes the holding coil 85 thus pulling its armature downwardly and breaking the contact at switch terminal 99, thereby de-energizing the hold-down coil 92 and opening the motor circuit at switch 95. Energization of the holding coil 66, when the boom has reached its selected position, also actuates a pawl I83 to release the ratchet disk I whereby its tension spring I84 returns it and the contact arm I8 to their normal positions of rest. This again opens the last named circuit and the control mechanism is automatically reset for another turning operation.

It is obvious that the control arrangement just described accurately positions the boom in any one of thirty-six positions throughout its one hundred and thirty-six degrees of rotation. Inasmuch as each contact 82 controls movement of the boom through a ten degree are, reasonably accurate tuning is accomplished, primarilybecause a signal forward is twenty degrees broad which is broader than the distance between any two positions of rest of the boom. However, more accurate tuning can be accomplished by providing more terminals 82 and 83.

The director or reflector structure illustrated in Fig. 6 also is vertically adjustable in length. In this embodiment, a sleeve I85 is rigidly anchored to the boom I I by two flanged externally threaded split clamps I86. An upper and a lower inner tube I91 extend into the sleeve I05 and each is rigidly secured therein by a bolt I88. Electrical contact between the sleeve and the tubes is assured by screwing the clamp nuts I89 tightly on the split clamps I86. Adjustment in thelength of the reflector or director is accomplished, in this instance, by providing internal threads at the lower end of the lower tube to receive a screw III] which normally extends a considerable distance therebelow. Adjustment of the screw is easily accomplished by engaging a tool in the screw-driver slot III at'its lower end. After-being adjusted, a lock nut H2 is tightened to prevent inadvertent displacement.

I claim:

1. An antenna system comprising, in combination, a fixed vertical radiator, a boom rotatable through ahorizontal plane around said radiator, said boom constituting a skeleton framework to minimize wind resistance, a plurality of telescoped vertically disposed members arranged in pairs on said boom, one pair on each side of said radiator, the members of each pair extending in' opposite directions, and means operable to adjust the length of both members of each pair in umson.

' -2.'An antenna system comprising, in combination, a boom rotatable through the horizontal plane, a plurality of telescoped vertically disposed members arranged in pairs on said boom, the members of each pair extending in opposite directions, a threaded shaft common to both members of a pair operatively connected with one telescoped section of each member, a. gear on said shaft between said members, an operating shaft, common to a plurality of pairs of members, and worm gears on said shaft one meshing with each of said first named gears whereby the length of each of said pairs of members is altered in unison upon rotation of said operating shaft.

3. In an antenna system including a tower, a horizontal boom rotatable on said tower, a director and a reflector mounted on said boom, said director and reflector each comprising, in combination, axially aligned tubing extending vertically in opposite directions from opposed faces of said boom, tubular extensions, one telescoped into the extended end of said tubing, internal threads on the inwardly disposed ends of said extensions, a shaft having right and left-hand threads engaging said internal threads, a cross shaft on said boom, a worm gear assembly operatively connecting said cross shaft with said threaded shaft, and manually operable means accessible at the bottom of said tower-operable to rotate said cross shaft to turn the threaded shaft and adjust the extensions in unison.

4. In an antenna system including a tower, a horizontally disposed boom rotatable around a vertical radiator at the upper end of said tower, at least one reflector and at least one director mounted adjacent opposite ends of said boom, said director and reflector each comprising, in combination, axially aligned tubing extending vertically in opposite directions from opposed faces of said boom, tubular extensions, one telescoped into the extended end of each tubing, internal threads on the inwardly disposed ends of said extensions, a shaft journaled in said extensions only having left and right-hand threads engaging said internal threads, a cross shaft on said boom, a worm gear assembly operatively connect- 7 ing said cross shaft with said threaded shaft, and

sions in unison.

5. In an antenna system, a vertical radiator, a horizontal boom rotatable about the, radiator, at least one vertical director on one arm of said boom, at least one vertical reflector on theother arm of said boom, and separate meansoperable at a distance from said radiator to rotate said boom and to adjust the lengths of saidrefiector and director.

6. A remote control system for a rotatable beam antenna, a motor operable to rotate said beam antenna, a solenoid, selectively operable means operable to transmit electrical impulses to said solenoid, a stepping device operable'upon energization of said solenoid to select one of a plurality of normally open control circuits, means to retain said stepping device in its selective position, a switch operable manually to close a main circuit to said motor, means to maintain said motor circuit closed upon release of said switch, a contact finger operable upon rotation of the beam for closing any one of said open control circuits, said contact finger operating to make the circuit selected by the stepping device upon reaching a position determined by initial operato turn the threadedshaft and adjust the extention' of thelselectively operable means whereby said stepping'device is freed to return to its initial position and the main circuit closing means is released to stop the motor.

7. In a remote control apparatus, a controlledv shaft movable into any one of a plurality of predetermined positions, a motor operatively connected with said shaft, a normally open circuit for said motor, a secondary circuit, a selector device including 'a contact arm in said secondary circuit, a plurality of contacts arranged to be selectively engaged by said contact arm, a secondset-of contacts, one electrically connected to each of the first named contacts, means operable to close the motor circuit and rotate said shaft, a

VV-ILLIAM SHEAR/LEAN BURKHART. 

